1 files changed, 87 insertions, 0 deletions
diff --git a/imagefile2png.c b/imagefile2png.c
new file mode 100644
index 0000000..cb170ff
--- /dev/null
+++ b/imagefile2png.c
@@ -0,0 +1,87 @@
+/* See LICENSE file for copyright and license details. */
+#include <arpa/inet.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include "arg.h"
+#include <png.h>
+
+char *argv0;
+
+#define HEADER_FORMAT "imagefile########"
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: %s\n", argv0);
+	exit(EXIT_FAILURE);
+}
+
+int
+main(int argc, char *argv[])
+{
+	png_structp png_struct_p;
+	png_infop png_info_p;
+	uint8_t hdr[17], *png_row;
+	uint32_t width, height, png_row_len, i;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc != 0)
+		usage();
+
+	/* header */
+	if (fread(hdr, 1, strlen(HEADER_FORMAT), stdin) != strlen(HEADER_FORMAT)) {
+		fprintf(stderr, "failed to read from stdin or input too short\n");
+		goto err;
+	}
+	if (strcmp("imagefile", hdr)) {
+		fprintf(stderr, "invalid header\n");
+		goto err;
+	}
+	width = ntohl((hdr[9] << 0) | (hdr[10] << 8) | (hdr[11] << 16) | (hdr[12] << 24));
+	height = ntohl((hdr[13] << 0) | (hdr[14] << 8) | (hdr[15] << 16) | (hdr[16] << 24));
+
+	/* load png */
+	png_struct_p = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	png_info_p = png_create_info_struct(png_struct_p);
+
+	if (!png_struct_p || !png_info_p || setjmp(png_jmpbuf(png_struct_p))) {
+		fprintf(stderr, "failed to initialize libpng\n");
+		goto err;
+	}
+	png_init_io(png_struct_p, stdout);
+	png_set_IHDR(png_struct_p, png_info_p, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
+		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+	png_write_info(png_struct_p, png_info_p);
+
+	/* write rows */
+	png_row_len = strlen("RGBA") * width * sizeof(uint8_t);
+	png_row = malloc(png_row_len);
+
+	for (i=0; i < height; ++i) {
+		if (fread(png_row, 1, png_row_len, stdin) != png_row_len) {
+			fprintf(stderr, "unexpected EOF or row-skew at %d\n", i);
+			goto err;
+		}
+		png_write_row(png_struct_p, png_row);
+	}
+	png_write_end(png_struct_p, NULL);
+
+	/* clean up */
+	png_free_data(png_struct_p, png_info_p, PNG_FREE_ALL, -1);
+	png_destroy_write_struct(&png_struct_p, NULL);
+	free(png_row);
+	return EXIT_SUCCESS;
+err:
+	png_free_data(png_struct_p, png_info_p, PNG_FREE_ALL, -1);
+	png_destroy_write_struct(&png_struct_p, NULL);
+	free(png_row);
+	return EXIT_FAILURE;
+}